Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 12/30/82

Final Date: 09/08/83

Deleted Date:

The Aerojet Rocketdyne Superfund site [note that Aerojet General Corporation acquired Rocketdyne, Inc. in 2013, and is operating as Aerojet Rocketdyne, Inc.] covers 5,900 acres near Rancho Cordova, 15 miles east of Sacramento. The northeastern edge of the site is about 1/2 mile from the American River. Since 1953, Aerojet and its subsidiaries manufactured liquid and solid propellant rocket engines for military and commercial applications and have formulated a number of chemicals, including rocket propellant agents, agricultural, pharmaceutical, and other industrial chemicals. In addition, the Cordova Chemical Company operated chemical manufacturing facilities on the Aerojet complex from 1974 to 1979. Both companies disposed of unknown quantities of hazardous waste chemicals, including trichloroethene (TCE) and other chemicals associated with rocket propellants, as well as various chemical processing wastes. Some wastes were disposed of in surface impoundments, landfills, deep injection wells, leachate fields, and some were disposed of by open burning. Underlying the site are extensive 40 to 100 foot-deep dredge tailings, a remnant of past gold mining operations.

In 1979, volatile organic compounds (VOCs) were found off-site in private wells and in the American River in 1983. Perchlorate, a component of solid rocket fuel, was found in drinking water wells off-site above the provisional reference dose range in January 1997. The communities potentially affected by this site are Rancho Cordova, population 61,000; Carmichael, population 68,000, Fair Oaks, population 41,000, and Gold River, population 9,000. The closest residence is about 500 feet away from the site. Groundwater is used extensively throughout the Rancho Cordova area to supply municipal, domestic, industrial and some irrigation water. Public and private drinking water supply wells have been contaminated and wells contaminated above response levels have been closed. Aerojet continues to monitor drinking water supplies to assure compliance with drinking water standards. Lake Natoma and Alder Creek are nearby and are used for recreational activities. The American River is a drinking water source, which receives indirect discharges from Aerojet's facility and groundwater treatment systems under National Pollution Discharge Elimination System (NPDES) permits.

Who is Involved

Investigation and Cleanup Activities

Change in cleanup approach: The 1989 Partial Consent Decree (PCD) for Remedial Investigation and Feasibility Study (RI/FS) was modified 4/15/02 to allow the site to be divided into Operable Units. The RI is a report detailing the nature and extent of contamination and the FS describes alternatives to address the contamination. Dividing the site into Operable Units (OUs) allows Aerojet and the regulating agencies to prioritize investigation and cleanup work; and accelerate cleanup.

The cleanup approach for the site under the modified PCD is to control groundwater contamination with two OUs, then remediate soil and groundwater at source areas (an additional 5 OUs). In 2001 EPA completed the Record of Decision for the long term groundwater cleanup of OU-3, the first groundwater action. The full construction of this action has been completed and the effectiveness of the groundwater containment systems are being evaluated. Many portions of the groundwater actions for OU-5 have also been completed and are in operation. The integrated plans for OU-5 including a number of contaminated soil areas were presented to the public in August 2009, and the final decision was formalized in February 2011. The first source area OU (OU-6) has completed the RI/FS process and a Proposed Plan was issued on May 1, 2013. Upon implementation of cleanup for the five source OUs, a cumulative risk review will be done to determine any further action required for the site as a whole.

Initial Actions

Interim Actions: Between 1983 and 1987, prior to the formal analysis and public process to select a long-term cleanup, five groundwater extraction and treatment (GET) facilities were installed as a barrier system, primarily to prevent further off-site movement of VOC contaminants. Each GET facility consists of a series of extraction wells and a groundwater treatment system to intercept contaminated groundwater before it moves off Aerojet property (GET A is in groundwater flow Zone 4, GET B is in groundwater flow Zone 3, GET D is in groundwater flow Zone 1, and GETs E and F in groundwater flow Zone 2). GETs E and F were combined in 1999 to provide for treatment of NDMA and perchlorate. GET E/F was further expanded in 2002 and in 2003 the discharge was diverted to the Buffalo Creek under an NPDES permit. GETs A and B discharge to Rebel Hill Ditch. GET A was moved to the GET B location in 2010. A sixth GET facility, the American River GET (AR GET) was placed in operation July 1998 to augment GET D VOC capture and discharges to Buffalo Creek.

As the long-term cleanup actions are determined through the RI/FS process culminating in a Record of Decision for each Operable Unit, any Interim Action is incorporated into the remedy selected.

Aerojet began a Time-Critical Removal Action in November 2009 to clean PCB- and metal-contaminated sediment from several drainage ditches and culverts in the Perimeter Operable Unit (OU-5) prior to weather conditions that could spread the contaminants. Final disposal of the 4,930 tons of soil was delayed by weather until the spring of 2010. EPA approved transfer of the soil to the Forward Class II landfill in Stockton. Aerojet submitted the final report on May 24 2010 and EPA finalized the Pollution Report completing the Removal Action the same day. EPA certified that Aerojet had fulfilled all requirements of the UAO to implement the Removal Action.

Site Studies

Entire Site: In 1983, with formal modification in 1998 and 2001, EPA ordered Aerojet to investigate the nature and extent of groundwater and soil contamination throughout the site with oversight by the U.S. EPA, the California Department of Toxic Substances Control (DTSC), and the Regional Water Quality Control Board (RWQCB). The investigation is phased to develop RI/FS reports for each individual OU, starting with OU-3 and OU-5 to ensure protectiveness from the groundwater contamination spreading beyond the property boundary.

Technology pilots are being conducted to assess in-situ bioremediation and other innovative technologies applicable to large scale groundwater remediation and methods to control dense non-aqueous phase liquids (DNAPL) and options available for DNAPL reduction.

Western Groundwater OU(OU-3): Studies to define the nature and extent of contamination of groundwater migrating from the western end of the Aerojet property were formally completed in 2001 when EPA signed a Record of Decision (ROD) specifying the selected groundwater cleanup plan for this part of the site.

Perimeter Groundwater OU(OU-5):In August 2002, the EPA and the State issued parallel orders to Aerojet to begin or expand critical work to achieve full containment of contaminated groundwater on the north and south side of Aerojet and prevent contamination from flowing off Aerojet's property. Aerojet was directed to conduct an RI/FS for the Perimeter Groundwater Operable Unit or OU-5 to address the groundwater and investigate 26 potential soil source areas located within Aerojet’s perimeter development plans. The RI/FS for OU-5 was submitted to the EPA's National Remedy Review Board October 6, 2005 for review of compliance with national policy.

Studies similar to those conducted for OU-3 for plumes emanating from the north and south boundaries of the Aerojet property for OU-5 were completed in June 2009, including an extensive site-specific study of the potential risks from VOC vapors to people living and working above the contaminated groundwater. EPA issued a Proposed Plan for the Perimeter Groundwater OU in August 2009. The public comment period was extended by request to October 1, 2009. On August 11, 2009, a public meeting was held to present the plan and take verbal comments at the City Hall of Rancho Cordova. The ROD was signed on February 15, 2011.

Boundary OU (OU-6) is the first of five source areas scheduled to be addressed by sequential RI/FS studies. The RI report was finalized in 2011, and the final FS report was issued in 2012. EPA issued a Proposed Plan based on the information in the RI/FS report in May 2013 with a public comment period of May 8, 2013 to June 7, 2013. On May 16, 2013, EPA received and approved a request to extend the public comment period to September 20, 2013. EPA plans to issue the Record of Decision on this Site later in 2015.

Cleanup plans for the remaining OUs will be presented for public comment as they are developed. An examination of the effectiveness, protectiveness and regulatory compliance of the remedies for the entire Aerojet Site will lead to a final site-wide cleanup plan once remedies for all of the individual OUs are selected.

Remedy Selected

The Proposed Plan for Western Groundwater (OU-3) was issued in November 2000 and public meetings were held December 7, 2000 and January 17, 2001. The EPA issued the ROD for OU-3 on July 20, 2001 and a Unilateral Administrative Order to Aerojet for the work on August 9, 2002. OU-3 will contain contaminated groundwater on the western side of Aerojet and restore the aquifer between the on and off-property control systems. There are fifteen Contaminants of Concern in OU-3 groundwater but the primary contaminants are TCE, perchlorate, and NDMA.

The Aerojet Record of Decision for the Perimeter Groundwater OU (OU-5) was signed on February 15, 2011 including a responsiveness summary to public comments received. The ROD selected an Interim Remedy for Groundwater and a final cleanup for the contaminated soil locations. The groundwater remedy will hydraulically contain the plume areas to prevent the spread of contamination, with additional pumping and treating to intercept and remove highly contaminated groundwater where possible. Within OU-5, there are 17 contaminants of concern identified although TCE, NDMA and perchlorate are the primary contaminants as in OU-3. In OU-5 there are four different groundwater areas and some of them require cleanup actions in other Operable Units to eliminate the contaminant source. We are considering this an interim groundwater remedy until the source areas are fully addressed. Most of the groundwater capture system is already in place and operating as part of the initial actions described above. The Soil Areas remedy is to excavate or otherwise clean the soil areas to levels protective for residential use. Fourteen contaminants of concern were identified in the soil areas, including metals and others that are not issues in groundwater. We recognize that there could be difficulty in achieving the desired cleanup levels in some of the soil areas, so the remedy includes a combination of engineering controls (such as intercepting soil vapor) and Institutional Controls (limiting the land use) as necessary.

Cleanup Ongoing

The final groundwater extraction and treatment system planned for the Western Operable Unit (OU-3) began operating in May 2010. At GET H (Area 1), the treatment plant and all extraction wells are operating. At GET J (Area 2), all ten extraction wells are in service. Combined GET E/F with 21 extraction well locations is fully operational. GET K (Area 3) extraction wells, pipelines and treatment systems in Rancho Cordova were completed and operational in 2009. The GET L (Area 4) Bajamont Way Treatment plant is across the American River from the Aerojet Facility in Carmichael and has been fully operational since 2008. GET L-A is also across the American River in Ancil Hoffman Park, a county park and golf course in the City of Carmichael. Treated water is used for irrigation of the County's golf course. EPA has been coordinating with Aerojet to design and oversee preparation of a rigorous Effectiveness Evaluation of the full OU-3 remedy, with a major working sessions held in 2010 and planned for 2011. Evaluation of the effectiveness of the systems will be conducted by EPA and the State until satisfactory containment of the contamination can be demonstrated. A formal public review of the remedy will be conducted by EPA every five years until all cleanup objects are attained. These Five-Year Reviews will examine ongoing work throughout the Aerojet Site, not only one Operable Unit.

The groundwater extraction and treatment system for the Perimeter Groundwater Operable Unit (OU-5) is close to full operation. Additional design and construction of extraction systems will proceed under orders from EPA and the State. The water treatment systems have been constructed, although treatment systems may be modified or expanded as needed in the future. Planning and cleanup are complete in several of the soil areas and others are proceeding rapidly with EPA oversight. The OU-5 groundwater containment is being examined In conjunction with the effectiveness evaluation of the OU-3 groundwater remedy.

Cleanup Results to Date

Nine groundwater extraction and treatment systems "GETs" are operating throughout the Aerojet site: ARGET, GET A/B, GET D,, GET E/F, GET H-A, GET J, GET K-A, GET L-A and GET L-B. Together they remove over 20 million gallons of contaminated groundwater each day on average.
Through the end of 2014, all the groundwater extraction and treatment systems at Aerojet in OU-3 and OU-5 have treated a cumulative total of 137 billion gallons of groundwater and removed more than one million pounds of chemical contaminants.

Western Groundwater OU-3: The Western Groundwater Operable Unit is containng the contaminated groundwater on the western side of Aerojet and eventually will restore the aquifer. All of the planned extraction wells and treatment systems are operating. Under the Unilateral Administrative Order that EPA issued to Aerojet to complete construction of the Western Groundwater remedy, Aerojet publishes a notice to the public annually, showing the current maximum extent of groundwater contamination in OU-3.

Documents and Reports

Community Involvement

Public Meetings:
Boundary Operable Unit 6 Proposed Plan Comment Period
EPA held a proposed plan public meeting on May 15, 2013 at 7pm at the Rancho Cordova City Hall, 2729 Prospect Park Dr., Rancho Cordova. On May 16, 2013, EPA received and approved a request to extend the comment period to September 20, 2013. Transcripts are provided in the Documents and Reports - Community Involvement section. Once the Record of Decision is completed for OU-6, it will include formal response to all public comments received. It will be posted in the Documents and Records - Record of Decision Section above and a copy sent to the local site repositories listed below. A notice will appear in the local when it is completed.

Community Advisory Group for Aerojet Superfund Issues
EPA meets with representatives of a variety of community interests since March 22, 2001, to provide information on establishing a Community Advisory Group (CAG) for the site. A CAG has been formed and holds bimonthly meetings. The CAG Chairperson is Janis Heple. The most recent available notes from the CAG meetings are located in the Documents and Reports - Community Involvement section. If you would like to come to an Aerojet CAG meeting, please send your email address to Jackie Lane, Community Involvement Coordinator at lane.jackie@epa.gov

Western Groundwater (OU-3) Proposed Plan Public Meeting
The EPA held two meetings for public comment on the Western Groundwater Proposed Plan, one on December 7, 2000, and the second on January 17, 2001. Transcripts are provided in the Documents and Reports - Community Involvement section. Formal Response to all public comments received are in the Record of Decision for OU-3, in the Documents and Records - Record of Decision section.

Perimeter Groundwater (OU-5) Proposed Plan Public Meeting
The EPA held one meeting for public comment on the Perimeter Groundwater Proposed Plan, August 11, 2009. EPA's Proposed Plan Presentation at that meeting and meeting transcripts are provided in the Documents and Reports - Community Involvement section. Formal Response to all public comments received are in Appendix A of the OU-5 Record of Decision, in the Documents and Records - Record of Decision section.